The present invention relates to a filter driving mechanism for an image recording device, and more particularly to a filter driving mechanism of a small size for an image recording device in which groups of filters such as color density correcting filters are disposed in a number of levels or layers between an original to be duplicated and a photosensitive member, and the layers of filter groups are independently moved to effect highly accurate color density correction or the like with a single filter or layers of filters.
One example of image recording member in the form of microcapsules containing a photosensitive composition is disclosed in Japanese Laid-Open Patent Publication No. 57-179836. The disclosed image recording member is a photosensitive member which employs capsules having a synthetic high-molecular resin wall containing a vinyl compound, a photopolymerization starter, and a colorant precursor. With this photosensitive member, microcapsules are hardened in the pattern of an image through exposure, and then the microcapsules which have not been hardened are broken under pressure to discharge the colorant precursor which then forms a colored image. A high-quality image can be obtained by a simple dry-type process. However, the disclosed photosensitive member is much lower in photosensitivity than photosensitive members which use silver halides such as photographic emulsions.
There has been developed a novel photosensitive member which has high sensitivity and can be processed to produce a high-quality image through a simple dry-type process (see Japanese Laid-Open Patent Publication No. 61-275742). The photosensitive member comprises a support coated with a photosensitive silver halide, a reducing agent, a polymerizable compound, and a color-image-forming material. At least the polymerizable compound and the color-image-forming material are encased in one microcapsule.
An image recording device for recording an image using such a photosensitive member is disclosed in detail in U.S. patent application Ser. No. 942654. In the disclosed image recording device, the photosensitive member is exposed to an image to produce a latent image thereon. Then, the photosensitive member is heated to develop the image by polymerize the polymerizable compound in an area where the latent image is present, thus generating a high-molecular compound to harden microcapsules. Finally, the photosensitive member is superposed under pressure on an image receptive member having an image receptive layer to which a color-image-forming material can be transferred, so that at least some of microcapsules in an area where no latent image is present are broken to transfer the color-image-forming material to the image receptive member for thereby forming a visible image.
In order to form a high-quality and clear visible image on the image receptive member in the above image recording device, various filters such as color density correcting filters are interposed between the photosensitive member and an original to be duplicated for exposing the photosensitive member to the image. This is because image quality may be lowered by a color density irregularity due to a reduction in the amount of light emitted from an exposure light source, a slight change in the mechanical position of a focusing optical system, or a change in the image magnification.
Various proposals have been made for moving the filters between the photosensitive member and the original to be copied. One example of such proposal is disclosed in Japanese Patent Publication No. 58-37535. FIG. 1 of the accompanying drawings illustrates the disclosed arrangement.
As shown in FIG. 1, an original 2 to be duplicated is illuminated with a light beam 6 emitted from a light source 4. The light beam 6 is reflected by the original 2 and applied to a convergent light transmitting body 8. The convergent light transmitting body 8 has an array of rod-shaped lenses 10 arranged in a main scanning direction (normal to the sheet of FIG. 1). The light beam 6 applied to the rod-shaped lenses 10 passes through a density filter 12 and is applied to a photosensitive member 14 to record an image thereon.
The density filter 12 has a plurality of density areas or portions 12a through 12n extending in the main scanning direction and having different optical densities. The amount of light applied to the photosensitive member 14 by the light beam 6 is adjusted by displacing the density filter 12 in the direction of the arrow to position a density area having a desired optical density, such as the density area 12b, below the rod-shaped lenses 10.
With the many different density filters 12a through 12n in the density filter 12, the length of the density filter 12 in a direction normal to the main scanning direction is considerably large. Therefore, a driving mechanism for displacing the density filter 12 back and forth in the direction of the arrow is large in size, and an image recording device in which the driving mechanism is to be incorporated cannot be reduced in size.
Where the density filter 12 is long, it has to be moved a considerable distance, and cannot be moved with high accuracy. As a result, a desired density area may not accurately be positioned below the convergent light transmitting body 8, and it is highly difficult to obtain a high-quality image on the photosensitive member 14.